tests: add on-board button test

tests/buttons/Makefile

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+APPLICATION = buttons
+include ../Makefile.tests_common
+
+USEMODULE += xtimer
+
+include $(RIOTBASE)/Makefile.include

tests/buttons/README.md

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+# On-Board Button Test
+
+This tests initializes all on-board buttons available, currently up to 4 in
+total. Each button is configured as an input with interrupt on button press
+or release depending on the configured TEST_FLANK.
+
+# Expected Result
+
+When a button is pressed (and/or released) an interrupt fires which results in
+a message indicating which button was used. The test naturally qualifies for
+manual testing only. Nevertheless, it prints "[SUCCESS]" after all buttons
+were initialized successfully or "[FAILED] <msg>" on error, so it can be used
+for limited automated testing as well.

tests/buttons/main.c

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+/*
+ * Copyright (C) 2017 HAW Hamburg
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser General
+ * Public License v2.1. See the file LICENSE in the top level directory for more
+ * details.
+ */
+
+/**
+ * @ingroup     tests
+ * @{
+ *
+ * @file
+ * @brief       Test for the on-board button macros
+ *
+ * @author      Sebastian Meiling <s@mlng.net>
+ *
+ * @}
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+
+#include "board.h"
+#include "periph/gpio.h"
+#include "periph_conf.h"
+
+#define TEST_FLANK      GPIO_FALLING
+
+#ifdef BTN0_PIN /* assuming that first button is always BTN0 */
+static void cb(void *arg)
+{
+    printf("Pressed BTN%d\n", (int)arg);
+}
+#endif
+
+int main(void)
+{
+    int cnt = 0;
+    /* get the number of available buttons and init interrupt handler */
+#ifdef BTN0_PIN
+    if (gpio_init_int(BTN0_PIN, BTN0_MODE, TEST_FLANK, cb, (void *)cnt) < 0) {
+        puts("[FAILED] init BTN0!");
+        return 1;
+    }
+    ++cnt;
+#endif
+#ifdef BTN1_PIN
+    if (gpio_init_int(BTN1_PIN, BTN1_MODE, TEST_FLANK, cb, (void *)cnt) < 0) {
+        puts("[FAILED] init BTN1!");
+        return 1;
+    }
+    ++cnt;
+#endif
+#ifdef BTN2_PIN
+    if (gpio_init_int(BTN2_PIN, BTN2_MODE, TEST_FLANK, cb, (void *)cnt) < 0) {
+        puts("[FAILED] init BTN2!");
+        return 1;
+    }
+    ++cnt;
+#endif
+#ifdef BTN3_PIN
+    if (gpio_init_int(BTN3_PIN, BTN3_MODE, TEST_FLANK, cb, (void *)cnt) < 0) {
+        puts("[FAILED] init BTN3!");
+        return 1;
+    }
+    ++cnt;
+#endif
+
+    puts("On-board button test\n");
+    /* cppcheck-suppress knownConditionTrueFalse
+     * rationale: board-dependent ifdefs */
+    if (cnt == 0) {
+        puts("[FAILED] no buttons available!");
+        return 2;
+    }
+    printf(" -- Available buttons: %i\n\n", cnt);
+    puts(" -- Try pressing buttons to test.\n");
+    puts("[SUCCESS]");
+    return 0;
+}